1 =============================
2 Configuring a Tahoe-LAFS node
3 =============================
6 2. `Overall Node Configuration`_
7 3. `Client Configuration`_
8 4. `Storage Server Configuration`_
9 5. `Frontend Configuration`_
10 6. `Running A Helper`_
11 7. `Running An Introducer`_
12 8. `Other Files in BASEDIR`_
16 A Tahoe-LAFS node is configured by writing to files in its base directory.
17 These files are read by the node when it starts, so each time you change
18 them, you need to restart the node.
20 The node also writes state to its base directory, so it will create files on
23 This document contains a complete list of the config files that are examined
24 by the client node, as well as the state files that you'll observe in its
27 The main file is named "``tahoe.cfg``", and is an ".INI"-style configuration
28 file (parsed by the Python stdlib 'ConfigParser' module: "``[name]``" section
29 markers, lines with "``key.subkey: value``", rfc822-style
30 continuations). There are also other files containing information that does
31 not easily fit into this format. The "``tahoe create-node``" or "``tahoe
32 create-client``" command will create an initial ``tahoe.cfg`` file for
33 you. After creation, the node will never modify the ``tahoe.cfg`` file: all
34 persistent state is put in other files.
36 The item descriptions below use the following types:
40 one of (True, yes, on, 1, False, off, no, 0), case-insensitive
44 a Twisted listening-port specification string, like "``tcp:80``" or
45 "``tcp:3456:interface=127.0.0.1``". For a full description of the format,
46 see `the Twisted strports documentation
47 <http://twistedmatrix.com/documents/current/api/twisted.application.strports.html>`_.
51 a Foolscap endpoint identifier, like
52 ``pb://soklj4y7eok5c3xkmjeqpw@192.168.69.247:44801/eqpwqtzm``
58 A node can be a client/server, an introducer, a statistics gatherer, or a
61 Client/server nodes provide one or more of the following services:
70 A client/server that provides storage service (i.e. storing shares for
71 clients) is called a "storage server". If it provides any of the other
72 services, it is a "storage client" (a node can be both a storage server and a
73 storage client). A client/server node that provides web-API service is called
77 Overall Node Configuration
78 ==========================
80 This section controls the network behavior of the node overall: which ports
81 and IP addresses are used, when connections are timed out, etc. This
82 configuration applies to all node types and is independent of the services
83 that the node is offering.
85 If your node is behind a firewall or NAT device and you want other clients to
86 connect to it, you'll need to open a port in the firewall or NAT, and specify
87 that port number in the tub.port option. If behind a NAT, you *may* need to
88 set the ``tub.location`` option described below.
92 ``nickname = (UTF-8 string, optional)``
94 This value will be displayed in management tools as this node's
95 "nickname". If not provided, the nickname will be set to "<unspecified>".
96 This string shall be a UTF-8 encoded Unicode string.
98 ``web.port = (strports string, optional)``
100 This controls where the node's web server should listen, providing node
101 status and, if the node is a client/server, providing web-API service as
102 defined in `webapi.rst <frontends/webapi.rst>_`.
104 This file contains a Twisted "strports" specification such as "``3456``"
105 or "``tcp:3456:interface=127.0.0.1``". The "``tahoe create-node``" or
106 "``tahoe create-client``" commands set the ``web.port`` to
107 "``tcp:3456:interface=127.0.0.1``" by default; this is overridable by the
108 ``--webport`` option. You can make it use SSL by writing
109 "``ssl:3456:privateKey=mykey.pem:certKey=cert.pem``" instead.
111 If this is not provided, the node will not run a web server.
113 ``web.static = (string, optional)``
115 This controls where the ``/static`` portion of the URL space is
116 served. The value is a directory name (``~username`` is allowed, and
117 non-absolute names are interpreted relative to the node's basedir), which
118 can contain HTML and other files. This can be used to serve a
119 Javascript-based frontend to the Tahoe-LAFS node, or other services.
121 The default value is "``public_html``", which will serve
122 ``BASEDIR/public_html`` . With the default settings,
123 ``http://127.0.0.1:3456/static/foo.html`` will serve the contents of
124 ``BASEDIR/public_html/foo.html`` .
126 ``tub.port = (integer, optional)``
128 This controls which port the node uses to accept Foolscap connections
129 from other nodes. If not provided, the node will ask the kernel for any
130 available port. The port will be written to a separate file (named
131 ``client.port`` or ``introducer.port``), so that subsequent runs will
132 re-use the same port.
134 ``tub.location = (string, optional)``
136 In addition to running as a client, each Tahoe-LAFS node also runs as a
137 server, listening for connections from other Tahoe-LAFS clients. The node
138 announces its location by publishing a "FURL" (a string with some
139 connection hints) to the Introducer. The string it publishes can be found
140 in ``BASEDIR/private/storage.furl`` . The ``tub.location`` configuration
141 controls what location is published in this announcement.
143 If you don't provide ``tub.location``, the node will try to figure out a
144 useful one by itself, by using tools like "``ifconfig``" to determine the
145 set of IP addresses on which it can be reached from nodes both near and
146 far. It will also include the TCP port number on which it is listening
147 (either the one specified by ``tub.port``, or whichever port was assigned
148 by the kernel when ``tub.port`` is left unspecified).
150 You might want to override this value if your node lives behind a
151 firewall that is doing inbound port forwarding, or if you are using other
152 proxies such that the local IP address or port number is not the same one
153 that remote clients should use to connect. You might also want to control
154 this when using a Tor proxy to avoid revealing your actual IP address
155 through the Introducer announcement.
157 The value is a comma-separated string of host:port location hints, like
160 123.45.67.89:8098,tahoe.example.com:8098,127.0.0.1:8098
164 * Emulate default behavior, assuming your host has IP address
165 123.45.67.89 and the kernel-allocated port number was 8098::
168 tub.location = 123.45.67.89:8098,127.0.0.1:8098
170 * Use a DNS name so you can change the IP address more easily::
173 tub.location = tahoe.example.com:8098
175 * Run a node behind a firewall (which has an external IP address) that
176 has been configured to forward port 7912 to our internal node's port
180 tub.location = external-firewall.example.com:7912
182 * Run a node behind a Tor proxy (perhaps via ``torsocks``), in
183 client-only mode (i.e. we can make outbound connections, but other
184 nodes will not be able to connect to us). The literal
185 '``unreachable.example.org``' will not resolve, but will serve as a
186 reminder to human observers that this node cannot be reached. "Don't
187 call us.. we'll call you"::
190 tub.location = unreachable.example.org:0
192 * Run a node behind a Tor proxy, and make the server available as a Tor
193 "hidden service". (This assumes that other clients are running their
194 node with ``torsocks``, such that they are prepared to connect to a
195 ``.onion`` address.) The hidden service must first be configured in
196 Tor, by giving it a local port number and then obtaining a ``.onion``
197 name, using something in the ``torrc`` file like::
199 HiddenServiceDir /var/lib/tor/hidden_services/tahoe
200 HiddenServicePort 29212 127.0.0.1:8098
202 once Tor is restarted, the ``.onion`` hostname will be in
203 ``/var/lib/tor/hidden_services/tahoe/hostname``. Then set up your
207 tub.location = ualhejtq2p7ohfbb.onion:29212
209 Most users will not need to set ``tub.location``.
211 ``log_gatherer.furl = (FURL, optional)``
213 If provided, this contains a single FURL string that is used to contact a
214 "log gatherer", which will be granted access to the logport. This can be
215 used to gather operational logs in a single place. Note that in previous
216 releases of Tahoe-LAFS, if an old-style ``BASEDIR/log_gatherer.furl``
217 file existed it would also be used in addition to this value, allowing
218 multiple log gatherers to be used at once. As of Tahoe-LAFS v1.9.0, an
219 old-style file is ignored and a warning will be emitted if one is
220 detected. This means that as of Tahoe-LAFS v1.9.0 you can have at most
221 one log gatherer per node. See ticket `#1423`_ about lifting this
222 restriction and letting you have multiple log gatherers.
224 .. _`#1423`: http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1423
226 ``timeout.keepalive = (integer in seconds, optional)``
228 ``timeout.disconnect = (integer in seconds, optional)``
230 If ``timeout.keepalive`` is provided, it is treated as an integral number
231 of seconds, and sets the Foolscap "keepalive timer" to that value. For
232 each connection to another node, if nothing has been heard for a while,
233 we will attempt to provoke the other end into saying something. The
234 duration of silence that passes before sending the PING will be between
235 KT and 2*KT. This is mainly intended to keep NAT boxes from expiring idle
236 TCP sessions, but also gives TCP's long-duration keepalive/disconnect
237 timers some traffic to work with. The default value is 240 (i.e. 4
240 If timeout.disconnect is provided, this is treated as an integral number
241 of seconds, and sets the Foolscap "disconnect timer" to that value. For
242 each connection to another node, if nothing has been heard for a while,
243 we will drop the connection. The duration of silence that passes before
244 dropping the connection will be between DT-2*KT and 2*DT+2*KT (please see
245 ticket `#521`_ for more details). If we are sending a large amount of
246 data to the other end (which takes more than DT-2*KT to deliver), we
247 might incorrectly drop the connection. The default behavior (when this
248 value is not provided) is to disable the disconnect timer.
250 See ticket `#521`_ for a discussion of how to pick these timeout values.
251 Using 30 minutes means we'll disconnect after 22 to 68 minutes of
252 inactivity. Receiving data will reset this timeout, however if we have
253 more than 22min of data in the outbound queue (such as 800kB in two
254 pipelined segments of 10 shares each) and the far end has no need to
255 contact us, our ping might be delayed, so we may disconnect them by
258 .. _`#521`: http://tahoe-lafs.org/trac/tahoe-lafs/ticket/521
260 ``ssh.port = (strports string, optional)``
262 ``ssh.authorized_keys_file = (filename, optional)``
264 This enables an SSH-based interactive Python shell, which can be used to
265 inspect the internal state of the node, for debugging. To cause the node
266 to accept SSH connections on port 8022 from the same keys as the rest of
271 ssh.authorized_keys_file = ~/.ssh/authorized_keys
273 ``tempdir = (string, optional)``
275 This specifies a temporary directory for the web-API server to use, for
276 holding large files while they are being uploaded. If a web-API client
277 attempts to upload a 10GB file, this tempdir will need to have at least
278 10GB available for the upload to complete.
280 The default value is the ``tmp`` directory in the node's base directory
281 (i.e. ``BASEDIR/tmp``), but it can be placed elsewhere. This directory is
282 used for files that usually (on a Unix system) go into ``/tmp``. The
283 string will be interpreted relative to the node's base directory.
291 ``introducer.furl = (FURL string, mandatory)``
293 This FURL tells the client how to connect to the introducer. Each
294 Tahoe-LAFS grid is defined by an introducer. The introducer's FURL is
295 created by the introducer node and written into its base directory when
296 it starts, whereupon it should be published to everyone who wishes to
297 attach a client to that grid
299 ``helper.furl = (FURL string, optional)``
301 If provided, the node will attempt to connect to and use the given helper
302 for uploads. See `<helper.rst>`_ for details.
304 ``key_generator.furl = (FURL string, optional)``
306 If provided, the node will attempt to connect to and use the given
307 key-generator service, using RSA keys from the external process rather
308 than generating its own.
310 ``stats_gatherer.furl = (FURL string, optional)``
312 If provided, the node will connect to the given stats gatherer and
313 provide it with operational statistics.
315 ``shares.needed = (int, optional) aka "k", default 3``
317 ``shares.total = (int, optional) aka "N", N >= k, default 10``
319 ``shares.happy = (int, optional) 1 <= happy <= N, default 7``
321 These three values set the default encoding parameters. Each time a new
322 file is uploaded, erasure-coding is used to break the ciphertext into
323 separate shares. There will be ``N`` (i.e. ``shares.total``) shares
324 created, and the file will be recoverable if any ``k``
325 (i.e. ``shares.needed``) shares are retrieved. The default values are
326 3-of-10 (i.e. ``shares.needed = 3``, ``shares.total = 10``). Setting
327 ``k`` to 1 is equivalent to simple replication (uploading ``N`` copies of
330 These values control the tradeoff between storage overhead and
331 reliability. To a first approximation, a 1MB file will use (1MB *
332 ``N``/``k``) of backend storage space (the actual value will be a bit
333 more, because of other forms of overhead). Up to ``N``-``k`` shares can
334 be lost before the file becomes unrecoverable. So large ``N``/``k``
335 ratios are more reliable, and small ``N``/``k`` ratios use less disk
336 space. ``N`` cannot be larger than 256, because of the 8-bit
337 erasure-coding algorithm that Tahoe-LAFS uses. ``k`` can not be greater
338 than ``N``. See `<performance.rst>`_ for more details.
340 ``shares.happy`` allows you control over how well to "spread out" the
341 shares of an immutable file. For a successful upload, shares are
342 guaranteed to be initially placed on at least ``shares.happy`` distinct
343 servers, the correct functioning of any ``k`` of which is sufficient to
344 guarantee the availability of the uploaded file. This value should not be
345 larger than the number of servers on your grid.
347 A value of ``shares.happy`` <= ``k`` is allowed, but does not provide any
348 redundancy if some servers fail or lose shares.
350 (Mutable files use a different share placement algorithm that does not
351 currently consider this parameter.)
353 ``mutable.format = sdmf or mdmf``
355 This value tells Tahoe-LAFS what the default mutable file format should
356 be. If ``mutable.format=sdmf``, then newly created mutable files will be
357 in the old SDMF format. This is desirable for clients that operate on
358 grids where some peers run older versions of Tahoe-LAFS, as these older
359 versions cannot read the new MDMF mutable file format. If
360 ``mutable.format`` is ``mdmf``, then newly created mutable files will use
361 the new MDMF format, which supports efficient in-place modification and
362 streaming downloads. You can overwrite this value using a special
363 mutable-type parameter in the webapi. If you do not specify a value here,
364 Tahoe-LAFS will use SDMF for all newly-created mutable files.
366 Note that this parameter only applies to mutable files. Mutable
367 directories, which are stored as mutable files, are not controlled by
368 this parameter and will always use SDMF. We may revisit this decision in
369 future versions of Tahoe-LAFS.
371 Frontend Configuration
372 ======================
374 The Tahoe client process can run a variety of frontend file-access protocols.
375 You will use these to create and retrieve files from the virtual filesystem.
376 Configuration details for each are documented in the following
377 protocol-specific guides:
381 Tahoe runs a webserver by default on port 3456. This interface provides a
382 human-oriented "WUI", with pages to create, modify, and browse
383 directories and files, as well as a number of pages to check on the
384 status of your Tahoe node. It also provides a machine-oriented "WAPI",
385 with a REST-ful HTTP interface that can be used by other programs
386 (including the CLI tools). Please see `<frontends/webapi.rst>`_ for full
387 details, and the ``web.port`` and ``web.static`` config variables above.
388 The `<frontends/download-status.rst>`_ document also describes a few WUI
393 The main "bin/tahoe" executable includes subcommands for manipulating the
394 filesystem, uploading/downloading files, and creating/running Tahoe
395 nodes. See `<frontends/CLI.rst>`_ for details.
399 Tahoe can also run both FTP and SFTP servers, and map a username/password
400 pair to a top-level Tahoe directory. See `<frontends/FTP-and-SFTP.rst>`_
401 for instructions on configuring these services, and the ``[ftpd]`` and
402 ``[sftpd]`` sections of ``tahoe.cfg``.
406 As of Tahoe-LAFS v1.9.0, a node running on Linux can be configured to
407 automatically upload files that are created or changed in a specified
408 local directory. See `<frontends/drop_upload.rst>`_ for details.
412 Storage Server Configuration
413 ============================
417 ``enabled = (boolean, optional)``
419 If this is ``True``, the node will run a storage server, offering space
420 to other clients. If it is ``False``, the node will not run a storage
421 server, meaning that no shares will be stored on this node. Use ``False``
422 for clients who do not wish to provide storage service. The default value
425 ``readonly = (boolean, optional)``
427 If ``True``, the node will run a storage server but will not accept any
428 shares, making it effectively read-only. Use this for storage servers
429 that are being decommissioned: the ``storage/`` directory could be
430 mounted read-only, while shares are moved to other servers. Note that
431 this currently only affects immutable shares. Mutable shares (used for
432 directories) will be written and modified anyway. See ticket `#390
433 <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/390>`_ for the current
434 status of this bug. The default value is ``False``.
436 ``reserved_space = (str, optional)``
438 If provided, this value defines how much disk space is reserved: the
439 storage server will not accept any share that causes the amount of free
440 disk space to drop below this value. (The free space is measured by a
441 call to statvfs(2) on Unix, or GetDiskFreeSpaceEx on Windows, and is the
442 space available to the user account under which the storage server runs.)
444 This string contains a number, with an optional case-insensitive scale
445 suffix like "K" or "M" or "G", and an optional "B" or "iB" suffix. So
446 "100MB", "100M", "100000000B", "100000000", and "100000kb" all mean the
447 same thing. Likewise, "1MiB", "1024KiB", and "1048576B" all mean the same
450 "``tahoe create-node``" generates a tahoe.cfg with
451 "``reserved_space=1G``", but you may wish to raise, lower, or remove the
452 reservation to suit your needs.
458 ``expire.override_lease_duration =``
460 ``expire.cutoff_date =``
462 ``expire.immutable =``
466 These settings control garbage collection, in which the server will
467 delete shares that no longer have an up-to-date lease on them. Please see
468 `<garbage-collection.rst>`_ for full details.
474 A "helper" is a regular client node that also offers the "upload helper"
479 ``enabled = (boolean, optional)``
481 If ``True``, the node will run a helper (see `<helper.rst>`_ for
482 details). The helper's contact FURL will be placed in
483 ``private/helper.furl``, from which it can be copied to any clients that
484 wish to use it. Clearly nodes should not both run a helper and attempt to
485 use one: do not create ``helper.furl`` and also define
486 ``[helper]enabled`` in the same node. The default is ``False``.
489 Running An Introducer
490 =====================
492 The introducer node uses a different ``.tac`` file (named
493 "``introducer.tac``"), and pays attention to the ``[node]`` section, but not
496 The Introducer node maintains some different state than regular client nodes.
498 ``BASEDIR/introducer.furl``
500 This is generated the first time the introducer node is started, and used
501 again on subsequent runs, to give the introduction service a persistent
502 long-term identity. This file should be published and copied into new
503 client nodes before they are started for the first time.
506 Other Files in BASEDIR
507 ======================
509 Some configuration is not kept in ``tahoe.cfg``, for the following reasons:
511 * it is generated by the node at startup, e.g. encryption keys. The node
512 never writes to ``tahoe.cfg``.
513 * it is generated by user action, e.g. the "``tahoe create-alias``" command.
515 In addition, non-configuration persistent state is kept in the node's base
516 directory, next to the configuration knobs.
518 This section describes these other files.
522 This contains an SSL private-key certificate. The node generates this the
523 first time it is started, and re-uses it on subsequent runs. This
524 certificate allows the node to have a cryptographically-strong identifier
525 (the Foolscap "TubID"), and to establish secure connections to other nodes.
529 Nodes that host StorageServers will create this directory to hold shares of
530 files on behalf of other clients. There will be a directory underneath it
531 for each StorageIndex for which this node is holding shares. There is also
532 an "incoming" directory where partially-completed shares are held while
533 they are being received.
537 This file defines the client, by constructing the actual Client instance
538 each time the node is started. It is used by the "``twistd``" daemonization
539 program (in the ``-y`` mode), which is run internally by the "``tahoe
540 start``" command. This file is created by the "``tahoe create-node``" or
541 "``tahoe create-client``" commands.
543 ``tahoe-introducer.tac``
545 This file is used to construct an introducer, and is created by the
546 "``tahoe create-introducer``" command.
548 ``tahoe-key-generator.tac``
550 This file is used to construct a key generator, and is created by the
551 "``tahoe create-key-gernerator``" command.
553 ``tahoe-stats-gatherer.tac``
555 This file is used to construct a statistics gatherer, and is created by the
556 "``tahoe create-stats-gatherer``" command.
558 ``private/control.furl``
560 This file contains a FURL that provides access to a control port on the
561 client node, from which files can be uploaded and downloaded. This file is
562 created with permissions that prevent anyone else from reading it (on
563 operating systems that support such a concept), to insure that only the
564 owner of the client node can use this feature. This port is intended for
565 debugging and testing use.
567 ``private/logport.furl``
569 This file contains a FURL that provides access to a 'log port' on the
570 client node, from which operational logs can be retrieved. Do not grant
571 logport access to strangers, because occasionally secret information may be
574 ``private/helper.furl``
576 If the node is running a helper (for use by other clients), its contact
577 FURL will be placed here. See `<helper.rst>`_ for more details.
579 ``private/root_dir.cap`` (optional)
581 The command-line tools will read a directory cap out of this file and use
582 it, if you don't specify a '--dir-cap' option or if you specify
585 ``private/convergence`` (automatically generated)
587 An added secret for encrypting immutable files. Everyone who has this same
588 string in their ``private/convergence`` file encrypts their immutable files
589 in the same way when uploading them. This causes identical files to
590 "converge" -- to share the same storage space since they have identical
591 ciphertext -- which conserves space and optimizes upload time, but it also
592 exposes file contents to the possibility of a brute-force attack by people
593 who know that string. In this attack, if the attacker can guess most of the
594 contents of a file, then they can use brute-force to learn the remaining
597 So the set of people who know your ``private/convergence`` string is the
598 set of people who converge their storage space with you when you and they
599 upload identical immutable files, and it is also the set of people who
600 could mount such an attack.
602 The content of the ``private/convergence`` file is a base-32 encoded
603 string. If the file doesn't exist, then when the Tahoe-LAFS client starts
604 up it will generate a random 256-bit string and write the base-32 encoding
605 of this string into the file. If you want to converge your immutable files
606 with as many people as possible, put the empty string (so that
607 ``private/convergence`` is a zero-length file).
615 Each Tahoe-LAFS node creates a directory to hold the log messages produced
616 as the node runs. These logfiles are created and rotated by the
617 "``twistd``" daemonization program, so ``logs/twistd.log`` will contain the
618 most recent messages, ``logs/twistd.log.1`` will contain the previous ones,
619 ``logs/twistd.log.2`` will be older still, and so on. ``twistd`` rotates
620 logfiles after they grow beyond 1MB in size. If the space consumed by
621 logfiles becomes troublesome, they should be pruned: a cron job to delete
622 all files that were created more than a month ago in this ``logs/``
623 directory should be sufficient.
627 this is written by all nodes after startup, and contains a base32-encoded
628 (i.e. human-readable) NodeID that identifies this specific node. This
629 NodeID is the same string that gets displayed on the web page (in the
630 "which peers am I connected to" list), and the shortened form (the first
631 few characters) is recorded in various log messages.
635 Gateway nodes may find it necessary to prohibit access to certain
636 files. The web-API has a facility to block access to filecaps by their
637 storage index, returning a 403 "Forbidden" error instead of the original
638 file. For more details, see the "Access Blacklist" section of
639 `<frontends/webapi.rst>`_.
645 The following is a sample ``tahoe.cfg`` file, containing values for some of
646 the keys described in the previous section. Note that this is not a
647 recommended configuration (most of these are not the default values), merely
653 nickname = Bob's Tahoe-LAFS Node
655 tub.location = 123.45.67.89:8098,44.55.66.77:8098
657 log_gatherer.furl = pb://soklj4y7eok5c3xkmjeqpw@192.168.69.247:44801/eqpwqtzm
658 timeout.keepalive = 240
659 timeout.disconnect = 1800
661 ssh.authorized_keys_file = ~/.ssh/authorized_keys
665 introducer.furl = pb://ok45ssoklj4y7eok5c3xkmj@tahoe.example:44801/ii3uumo
666 helper.furl = pb://ggti5ssoklj4y7eok5c3xkmj@helper.tahoe.example:7054/kk8lhr
672 sizelimit = 10000000000
679 Old Configuration Files
680 =======================
682 Tahoe-LAFS releases before v1.3.0 had no ``tahoe.cfg`` file, and used
683 distinct files for each item. This is no longer supported and if you have
684 configuration in the old format you must manually convert it to the new
685 format for Tahoe-LAFS to detect it. See `<historical/configuration.rst>`_.